Effects Of GLP-1 (7-36) On High Glucose-induced Apoptosis Of Human Umbilical Vein Endothelial Cells (HUVECs) And The Mechanisms Involved

Objective:To investigate the effects of GLP-1 (7-36) on high glucose-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and the mechanism involved.Methods:HUVECs were cultured at 5mmol/l and 33mmol/l glucose in different concentrations of GLP-1 (7-36)(0 nmol/l,0.3 nmol/l,3nmol/l, 30nmol/l) for 24h,48h,72h respectively. Cell viability was then spectrophotometrically measured using an MTT assay under different conditions to determine the appropriate intervention period and concentration points.The experiment was grouped as follows:①normal glucose control group (NG),②high glucose injured group (HG),③high glucose injured group with added 3nmol/l GLP-1 (7-36) (HG+GLP-1),④normal glucose control group with added 3nmol/l GLP-1 (7-36) (NG+GLP-1),⑤HG+GLP-1 group with pretreated phosphatidylinositol 3'kinase inhibitor (HG+GLP-1+Wortmannin)⑥HG+GLP-1 group with pretreated endothelial nitric oxide synthase inhibitor (HG+GLP-1+L-NAME). All these groups were then analyzed by flow cytometry, western blot and nitric oxide assay kit to detect the ratio of cell apoptosis, protein levels of p-AKt and p-eNOS, and NO concentration respectively.Results:(1) The HUVEC's' viability under high glucose culture solution for 48h,72h was decreased compared to normal glucose culture solution. Treatment with GLP-1 (7-36) (3 nmol/l,30nmol/l) in the high glucose group for 48h and 72h significantly increased the HUVECs viability than that without GLP-1 (7-36) (p<0.01),but different concentrations of GLP-1 (7-36) at the same intervention interval had no difference (p>0.05). (2)Compared with the NG group, the ratio of HUVEC's' early apoptosis in the HG group was significantly increased (p<0.01), while the protein levels of p-AKt and p-eNOS and the NO production were significantly decreased(p<0.05); (3)Compared with the HG group, the ratio of HUVEC's' early apoptosis in the HG+GLP-1 group was significantly decreased (p<0.05),while the protein levels of p-AKt and p-eNOS and the NO production were significantly increased (p<0.05); (4) Compared with the HG+GLP-1 group, the ratio of HUVEC's' early apoptosis in the HG+GLP-1+Wortmannin group was significantly increased (p<0.05), while the protein levels of p-AKt and p-eNOS and the NO production were significantly decreased (p<0.05); (5) Compared with the HG+GLP-1 group, the ratio of HUVEC's' early apoptosis in the HG+GLP-1+L-NAME group was significantly increased (p<0.05), while the NO production was significantly decreased (p<0.05), and no significant difference could be observed on the protein levels of p-AKt.Conclusions:GLP-1 could ameliorate high glucose-induced HUVECs' apoptosis, the PI3K/AKt/eNOS pathway may play a role in this anti-apoptotic effect.